The present invention relates in general to a television transmission system and in particular to an adaptive TV transmission system for use in connection with another TV system employing standard number of scanning lines in its video signal.
In German magazine "Fernseh und Kinotechnik" 1980, No. 2, pages 41 through 48, different TV systems have been described in which the resolution and other quality factors of the reproduced pictures are improved in comparison with those in conventional TV transmission systems. If such new systems are to be employed in TV communications, it would be necessary to make them compatible with the existing ones. That means that transmissions produced according to the new methods should be received by established TV receivers withouts impairment of their quality. To achieve this, in the aforementioned publication several methods are devised which however have not yet been reduced to practice on a broader base.
In U.S. patent application Ser. No. 530,073 a high quality TV system which is compatible with existing standard TV systems has been devised in which the scanning of pictures is made progressively, that means without the line interlacing at a double line rate within a half frame or picture field of a standard TV signal so that the duration of a scanning line is only a quarter of the duration of the standard scanning lines. As a consequence, for processing such high quality TV signals, additional expansion circuits are necessary.